In animal studies and even in clinical studies the hydroxyapatite (HA) coated screw retained the highest level of osseointegration. However, the fixation for HAscrews is, especially in diaphyseal bone, the risk for too tight fixation, with extreme difficulties to remove the screws in few cases as a result ( high pain and seldom it is impossible to remove the screw) Coating by biphosphonate is a new novel technique with preclinical appealing performance, which theoretically should make this coating very appealing in clinical practice. The theory behind this technique is that it create a good pinfixation reasonable easy to remove.